Conjugated dienes, such as butadiene, present an intriguing possible source of a variety of more valuable chemicals. Conjugated dienes, obtained from various sources such as the conversion of refinery streams obtainable in the modern integrated refinery sometimes termed a petrocomplex, are relatively cheap chemicals. Conversion of such unsaturates potentially could provide routes to many other useful and valuable intermediates and end products. For example, 1,4-butanediol is a valuable intermediate used in the preparation of polybutylene terephthalate, an engineering type plastic.